The present invention relates to the locking of a mixing valve for hot and cold water and more in particular to a locking device to fix such a valve into the body of a water tap.
Several well known mixing taps comprise, inside a cartridge type body with bottom and cover, two overlapping disks made of ceramic or a similar material, one of which is fixed while the other one is movable, the fixed disk having two inlet openings for the hot and cold water delivered by two conduits and one outlet opening to deliver the water to the spout of a tap, the movable disk being displaced and positioned by means of a control lever swinging on a transversal axis and rotating around a vertical axis and comprising a mixing chamber to displace on and in respect to the openings in the fixed disk.
The whole assembly is designed in such a way that the cartridge type body of the mixing valve can be fixed, by interposing suitable packings, to the bottom of a seat inside the body of a tap fitted with inlet pipes for hot and cold water and with a water outlet spout.
According to a known execution, the cartridge type body, i.e. the mixing valve, is fixed into the body of the tap by means of a number of screws inserted from its top and engaging the bottom of the seat. This system is however hardly used, also because it is not very satisfactory and rather complicated.
In another known execution the cartridge type body, i.e. the mixing valve, is fixed into the body of the tap by means of a locking nut screwed on top of the tap and directly leaning on the cover of the cartridge. Locking nuts are largely used to fasten this kind of cartridges, they however have the disadvantage to act as a rather rigid locking means as they are unable to suit eventual working errors or defects of the tap body, especially those concerning the depth of its seat. Owing to this perculiarity the kind of locking they achieve may be either too tight or too loose or even insufficient and thus jeopardize the correct operation of the mixing valve. In fact, it cannot be excluded that the nut bears on the top of the body of the tap and gets locked without suitably blocking the cartridge if the seat inside the tap is too deep or, on the contrary, that the nut lock the cartridge too tightly to the bottom of the seat owing to its insufficient depth. In the first case the cartridge might get loose inside the tap, while in the second case it might not be able to operate correctly.